Because Nichiren Daishonin propagated His teachings in Kamakura, He was subjected to ploys from believers of other sects who joined hands with the shogunate. Vice Chief of the Samurai Office, Hei no Saemon-no-jo Yoritsuna, arrested the Daishonin on September 12^th 1271. Then at midnight, he secretly took the Daishonin to Tatsunokuchi and attempted to have the Daishonin beheaded. This is referred to as the Tatsunokuchi Persecution.
Immediately preceding the attempted beheading at Tatsunokuchi, a bright spherical light traveled across the dark sky from the direction of Enoshima. All samurai froze in debilitating fear, and were unable to complete the beheading.
Because of this, the Daishonin was exiled to Sado Island.